| 1. |
- Novotny, Renata, et al.
(författare)
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Conversion of Synthetic A beta to In Vivo Active Seeds and Amyloid Plaque Formation in a Hippocampal Slice Culture Model
- 2016
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Ingår i: Journal of Neuroscience. - : SOC NEUROSCIENCE. - 0270-6474 .- 1529-2401. ; 36:18, s. 5084-5093
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Tidskriftsartikel (refereegranskat)abstract
- The aggregation of amyloid-beta peptide (A beta) inbrain is an early event and hallmark of Alzheimers disease (AD). We combined the advantages of in vitro and in vivo approaches to study cerebral beta-amyloidosis by establishing a long-term hippocampal slice culture(HSC) model. While no A beta deposition was noted in untreated HSCs of postnatal A beta precursor protein transgenic (APP tg) mice, A beta deposition emerged in HSCs when cultures were treated once with brain extract from aged APP tg mice and the culture medium was continuously supplemented with synthetic A beta. Seeded A beta deposition was also observed under the same conditions in HSCs derived from wild-type or App-null mice but in no comparable way when HSCs were fixed before cultivation. Both the nature of the brain extract and the synthetic A beta species determined the conformational characteristics of HSCA beta deposition. HSCA beta deposits induced a microglia response, spine loss, and neuritic dystrophy but no obvious neuron loss. Remarkably, in contrast to in vitro aggregated synthetic A beta, homogenates of A beta deposits containing HSCs induced cerebral beta-amyloidosis upon intracerebral inoculation into young APP tg mice. Our results demonstrate that a living cellular environment promotes the seeded conversion of synthetic A beta into a potent in vivo seeding-active form.
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| 2. |
- Wagner, Jessica, et al.
(författare)
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Medin co-aggregates with vascular amyloid-beta in Alzheimers disease
- 2022
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Ingår i: Nature. - : Nature Portfolio. - 0028-0836 .- 1476-4687. ; 612, s. 123-131
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Tidskriftsartikel (refereegranskat)abstract
- Aggregates of medin amyloid (a fragment of the protein MFG-E8, also known as lactadherin) are found in the vasculature of almost all humans over 50 years of age(1,)(2), making it the most common amyloid currently known. We recently reported that medin also aggregates in blood vessels of ageing wild-type mice, causing cerebrovascular dysfunction(3). Here we demonstrate in amyloid-beta precursor protein (APP) transgenic mice and in patients with Alzheimers disease that medin co-localizes with vascular amyloid-beta deposits, and that in mice, medin deficiency reduces vascular amyloid-beta deposition by half. Moreover, in both the mouse and human brain, MFG-E8 is highly enriched in the vasculature and both MFG-E8 and medin levels increase with the severity of vascular amyloid-beta burden. Additionally, analysing data from 566 individuals in the ROSMAP cohort, we find that patients with Alzheimers disease have higher MFGE8 expression levels, which are attributable to vascular cells and are associated with increased measures of cognitive decline, independent of plaque and tau pathology. Mechanistically, we demonstrate that medin interacts directly with amyloid-beta to promote its aggregation, as medin forms heterologous fibrils with amyloid-beta, affects amyloid-beta fibril structure, and cross-seeds amyloid-beta aggregation both in vitro and in vivo. Thus, medin could be a therapeutic target for prevention of vascular damage and cognitive decline resulting from amyloid-beta deposition in the blood vessels of the brain.
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